Vehicle door latch assemblies frequently incorporate a door handle grip that is pulled away from the door in order to operate the latch mechanism and open the door. In the event of an impact event such as a collision, particularly one that generates an impact force vector perpendicular to the side of the vehicle, the acceleration of the vehicle in the direction of the side-acting force vector can cause the door (plus the rest of the vehicle) to accelerate away from the door handle grip due to the inertia of the door handle grip. Such impact events typically consist of two phases: an acceleration phase and a deformation phase.
The acceleration phase corresponds to a period of time commencing with the initial impact. During this time, which is typically about 40 msec duration but can extend to about 300 msec duration, a release handle assembly in the area of the impact can experience relatively high accelerations, and, consequently, relatively high acceleration forces, associated with primarily lateral movement of the vehicle door. This generates relative movement analogous to pulling on the door handle grip to open the door.
During the deformation phase, which ensues after the acceleration phase, crushing and deformation of the side structure of the vehicle occurs in the area affected by impact forces. During this time, acceleration of the door latch assembly is somewhat asymptotically reduced to zero. Nevertheless, depending upon specific impact event parameters, the potential for the vehicle door to open still exists during the deformation phase. As well, the vehicle door may be able to open during the end of the acceleration phase in certain events having an extended acceleration phase.
In order to minimize the potential for unintended impact-induced door opening, vehicle door release handle suppliers have developed inertial blocking member subassemblies that impede the unintended movement of the release handle assembly and/or door opening actuator resulting from an impact to the vehicle. These subassemblies are activated between an at-rest position, wherein the door, if functional, can be opened by operating the release handle assembly, and a blocking position, wherein opening of the door is prevented by impact-generated inertial forces. Impeding the movement of the release handle assembly or door opening actuator can thus be accomplished by controlling impact-based acceleration and inertial effects associated with the inertial blocking member subassembly.
Known inertial blocking member subassemblies are configured, generally with a biasing element, to return to the at-rest position, which enables the door to be opened in the usual manner in the absence of, or after, an impact event. However, known inertial blocking member subassemblies are typically only effective during the acceleration phase; they generally return to their at-rest position during or after the deformation phase, which enables the release handle assembly to operate, thereby enabling occupants to exit the vehicle and emergency personnel to readily access occupants remaining in the vehicle. This functionality can also enable the door to be unintentionally opened during the deformation phase of an impact event.
Unintended post-impact door opening can be minimized by an inertial blocking member subassembly that maintains its “blocking” position for a selected time after the impact event has terminated, rather than enabling the subassembly to return to an at-rest position. However, to extend the duration of the blocking action by controlling the return of the inertial blocking member to its at-rest position may prevent opening of the door after the impact event has terminated, which may be a potentially serious threat to occupants remaining in the vehicle.
An inertial blocking member subassembly configured to prevent the unintended opening of the door during the acceleration and deformation phases, while enabling the operation of the door release handle to open the door after the end of the impact event, would be desirable.